In recent years, local area networks utilizing wireless communication (hereinafter referred to as “wireless LANs”) have become popular, and it is possible to use wireless communication terminals connected to wireless LANs as IP (Internet Protocol) telephones. Conventional mobile phones are each provided with a communication function that makes a telephone call or the like by making a wireless connection to a network provided by a telephone service provider, and in addition to this communication function, it is possible to install a function that establishes a communication by making a wireless connection to a wireless LAN and use a mobile phone as an IP phone. However, not all mobile phones would need to function as IP phones, and there is a need for a mobile phone that enables selection as to whether the mobile phone functions as an IP phone as desired by a user thereof.
Mobile phones each have a telephone directory function and store telephone directory data that associates telephone numbers for making calls to telephones of called parties with the names or the like of the called parties. Use of this telephone directory data is convenient in that there is no need for remembering telephone numbers assigned to the telephones of the called parties. In the case where a mobile phone functions as an IP phone, in order to make a call to another IP phone connectable to the wireless LAN, it is necessary to make a call to the telephone number assigned to the other IP phone, and this telephone number differs from the one assigned to the mobile phone by the telephone service provider. This requires the telephone directory data to separately store the telephone number assigned to the mobile phone and the telephone number assigned to the IP phone (this telephone number being hereinafter referred to as an “extension number”).
Japanese Patent Laid-Open No. 10-126851 (Patent Document 1) discloses an information processing device that stores two kinds of telephone numbers in one piece of telephone directory data, although this is not a mobile phone that can be used as a mobile phone and an IP phone. The information processing device disclosed in Japanese Patent Laid-Open No. 10-126851 is provided with a telephone function that has at least two communication modes including a public mode and a transceiver mode, and characterized in including: storing means of storing a normal telephone number used in the public mode and an extension number used in the transceiver mode in association with a name; specifying means of specifying the name of a called party; extension number judging means of judging whether the storing means stores an extension number that corresponds to the name of the called party specified by the specifying means; and communication mode switching means of, as a result of the extension number judgment, switching to the transceiver mode when the storing means stores an extension number corresponding to the name of the called party and reading the extension number corresponding to the name of the called party from the storing means to make a call to the extension number, while when the storing means stores no extension numbers corresponding to the name of the called party, switching to the public mode and reading a normal telephone number that corresponds to the name of the called party from the storing means to make a call to the telephone number.
However, even when the conventional information processing device is applied to a mobile phone that can also be used as an IP phone, the following problem arises. The problem is that in the case where the user of the mobile phone does not want it to function as an IP phone, displaying a telephone number assigned to the IP phone results in a display of unnecessary information. In particular, since mobile phones are small and limited in size for the display screens, unnecessary information is preferably not displayed.
Additionally, there is the problem that for the protocols for establishing a communication by connecting mobile phones to wireless LANs, the protocols are standardized in the lower layers of the OSI layer model, but in the upper layers, the protocols may vary for a plurality of kinds of wireless LANs.    [Patent Document 1] Japanese Patent Laid-Open No. 10-126851